The existence of the unsolvated 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) dianion is proved experimentally. The dianion was formed in 50-keV collisions between TCNQ monoanions and sodium vapor. In the collision process, electron capture to the monoanion occurs with a cross section of about 1 Angstrom(2). The lifetime of the dianion is estimated to be in the order of microseconds or longer as the flight time from the collision cell to the detector is 5 mus. The stability of the dianion was elucidated by density functional theory (DFT) and ab initio MP2 calculations. A selection of dissociation reactions have been studied theoretically and compared with the experimental results. (C) 2003 American Institute of Physics.